It is known to provide a cladding body on the leading or trailing edge of blades, e.g. fan blades, in turbine engines; especially in gas turbine engines.
Such a cladding body provides a shield, typically along the entire length of an edge of the blade. The edge may be the leading or the trailing edge of the blade. The leading edge is located upstream, and the trailing edge is located downstream, when the engine is in use.
Cladding bodies are used to provide impact protection for the blade itself, for example against debris or bird strike. The blade may be formed of a composite material which is not able to withstand high energy impacts; indeed it may be hollow. Thus, the risk of damage to the blade often necessitates the use of a cladding body to provide sufficient shielding from such impacts, and may also provide some erosion protection to the blade.
Prior art cladding bodies typically exhibited a square bottomed slot at the root of the body, for example such as that shown in FIG. 3. The square bottomed slot geometry is problematic however, because it creates regions of high stress at the square corners susceptible to failure at relatively low impact energies.
US2012/0317810 discloses a method which eradicates the square bottomed slot at the root of the body. However, the process may result in other problems in the resultant cladding body, for example due to the exceptionally high level of deformation required by the superplastic formed membrane to conform in the region indicated by reference numeral 31 in FIG. 6 of US2012/0317810. Indeed, the amount of superplastic forming required to deform the planar metal sheet 60 of US2012/0317810 to conform to the insert 41 and blank 51 of US2012/0317810 may result in significant uneven material thickness of the cladding body.
Certainly, a significant amount of the material present in the original planar metal sheet 60 of US2012/0317810 will be wasted. Indeed, from e.g. FIGS. 5 and 6 of US2012/0317810 it is conceivable that in excess of 50% of the original material of planar metal sheet 60 of US2012/0317810 may be wasted.